A spectrally selective surface structure for combined photothermic conversion and radiative sky cooling

• Published in: Frontiers in Energy Vol. 14; no. 4; pp. 882 - 888
• Main Authors: ZHAO, Bin, AO, Xianze, CHEN, Nuo, XUAN, Qingdong, HU, Mingke, PEI, Gang
• Format: Journal Article
• Language: English
• Published: Beijing Higher Education Press 2020; Springer Nature B.V
• Subjects: Absorptivity; Ambient temperature; Atmospheric windows; Conversion; Cooling; Emissivity; Emitters; Energy; Energy harvesting; Energy Systems; Infrared spectra; multilayer film; Night; Nighttime; photothermic conversion; Polydimethylsiloxane; radiative sky cooling; Renewable energy; Research Article; Selective surfaces; Sky; solar energy; Solar energy absorbers; Spectral emittance; spectral selectivity; Surface structure; Thermal analysis; multilayer film; solar energy; radiative sky cooling; spectral selectivity; photothermic conversion
• ISSN: 2095-1701; 2095-1698
• DOI: 10.1007/s11708-020-0694-z

The sun and outer space are the ultimate heat and cold sources for the earth, respectively. They have significant potential for renewable energy harvesting. In this paper, a spectrally selective surface structure that has a planar polydimethylsiloxane layer covering a solar absorber is conceptually proposed and optically designed for the combination of photothermic conversion (PT) and nighttime radiative sky cooling (RC). An optical simulation is conducted whose result shows that the designed surface structure (i.e., PT-RC surface structure) has a strong solar absorption coefficient of 0.92 and simultaneously emits as a mid-infrared spectral-selective emitter with an average emissivity of 0.84 within the atmospheric window. A thermal analysis prediction reveals that the designed PT-RC surface structure can be heated to 79.1°C higher than the ambient temperature in the daytime and passively cooled below the ambient temperature of approximately 10°C in the nighttime, indicating that the designed PT-RC surface structure has the potential for integrated PT conversion and nighttime RC utilization.